1. Field of the Invention
The present invention relates to a display device capable of detecting an object such as user's finger or pen coming in contact with or proximity to the display surface, and to a driving method of the same.
2. Description of the Related Art
Three methods, namely, optical method, resistance film method and electrostatic capacitance method, are known as the contact detection methods of a touch panel.
In order to associate the electrical change resulting from an object coming in contact or proximity with positional information, on the other hand, a number of wirings are required that are arranged in a matrix form and combined in such a manner as to allow identification of positions. An enormous number of wirings are necessary to provide improved detection resolution if position detection is conducted based on combinations of the wirings.
For this reason, one driving method is on its way to becoming mainstream in the above three detection methods. This driving method detects the contact or
proximity position while at the same time scanning, in one direction, the lines adapted to output the electrical change. This driving method is described in Hirotaka Hayashi etc. “Optical Sensor Embedded Input Display Usable under High-Ambient-Light Conditions,” SID 07 DIGEST p 1105 (hereinafter referred to as Non-Patent Document 1) for the optical method, in Bong Hyun Youetc., “12.1-inch a-Si:H TFT LCD with Embedded Touch Screen Panel,” SID 08 DIGEST p 830 (hereinafter referred to as Non-Patent Document 2) for the resistance film method, and in Joohyung Lee etc., “Hybrid Touch Screen Panel Integrated in TFT-LCD,” SID 08 DIGEST p 834 (hereinafter referred to as Non-Patent Document 3) for the electrostatic capacitance method. Here, the term “lines” refers to rows or columns of extremely small sensor sections that are arranged two-dimensionally according to a predetermined rule for contact detection purposes.
Incidentally, overlaying a touch panel on a display panel leads to a thicker display module as a whole, resulting in increased area of the frame (portion around the effective detection surface) and increased cost.
Therefore, recent years have seen transitions in mainstream types of developed display modules from that having the touch panel overlaid on the display panel to that having the touch panel incorporated in the display panel (refer, for example, to the above Non-Patent Documents 1 to 3 and to Japanese Patent Laid-Open No. 2008-9750).